1. Field of the Invention
The present invention relates to a method and apparatus for drying semiconductor materials, such as silicon wafers or glass photomasks, placed in a carrier by mounting the carrier on a rotor and spinning the rotor, whereby water droplets stuck on surfaces of the semiconductor materials are removed and dried by centrifugal force.
2. Description of the Related Art
Spin dryers have conventionally been used for removing water from semiconductor materials and drying the semiconductor materials. These spin dryers are each constructed of a spin dryer main body, which comprises a rotor to be driven and spun and a casing enclosing a periphery and bottom part of the rotor, and a filter box disposed openably on the casing. Semiconductor materials are dried by closing the filter box and spinning the rotor. Namely, water stuck on surfaces of the semiconductor materials is outwardly blown off by centrifugal force developed as a result of spinning of the rotor. In addition, the spinning of the rotor produces a negative pressure in a central zone of the rotor, whereby air is drawn downwardly toward the rotor. The air so drawn then passes through the filter box so that the air is filtered. This filtered air next enters the rotor and flows radially and outwardly from the central zone of the rotor. The air thereafter flows out through an exhaust port formed in the casing which encloses the rotor. The semiconductor materials on the rotor are dried by such an air stream. The semiconductor materials to be dried in the above manner are however those washed with purified water immediately before the drying. In the state mounted on the rotor for spin-drying, water therefore still remains on the carrier and the individual semiconductor materials placed therein, leading to problems as will be described next.
Because it takes some time until semiconductors are placed in a spin dryer and is dried after their washing, the semiconductor materials are oxidized by purified water still remaining on their surfaces during this period. Where the semiconductor materials are memory devices, bit errors may be produced at gate regions, resulting in the drawback that their function as a memory may be impaired. Further, the diffusion rate of a dopant may become uneven in diffusing contact well regions so that control of the concentration of the dopant thus diffused may become difficult. In addition, in the case of aluminum wiring, there are problems such as the occurrence of disconnection and short circuits.